drivers/watchdog/lantiq_wdt.c

   1 /*
   2  *  This program is free software; you can redistribute it and/or modify it
   3  *  under the terms of the GNU General Public License version 2 as published
   4  *  by the Free Software Foundation.
   5  *
   6  *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
   7  *  Based on EP93xx wdt driver
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/module.h>
  13 #include <linux/fs.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/watchdog.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/uaccess.h>
  18 #include <linux/clk.h>
  19 #include <linux/io.h>
  20
  21 #include <lantiq.h>
  22
  23 /* Section 3.4 of the datasheet
  24  * The password sequence protects the WDT control register from unintended
  25  * write actions, which might cause malfunction of the WDT.
  26  *
  27  * essentially the following two magic passwords need to be written to allow
  28  * IO access to the WDT core
  29  */
  30 #define LTQ_WDT_PW1             0x00BE0000
  31 #define LTQ_WDT_PW2             0x00DC0000
  32
  33 #define LTQ_WDT_CR              0x0     /* watchdog control register */
  34 #define LTQ_WDT_SR              0x8     /* watchdog status register */
  35
  36 #define LTQ_WDT_SR_EN           (0x1 << 31)     /* enable bit */
  37 #define LTQ_WDT_SR_PWD          (0x3 << 26)     /* turn on power */
  38 #define LTQ_WDT_SR_CLKDIV       (0x3 << 24)     /* turn on clock and set */
  39                                                 /* divider to 0x40000 */
  40 #define LTQ_WDT_DIVIDER         0x40000
  41 #define LTQ_MAX_TIMEOUT         ((1 << 16) - 1) /* the reload field is 16 bit */
  42
  43 static bool nowayout = WATCHDOG_NOWAYOUT;
  44
  45 static void __iomem *ltq_wdt_membase;
  46 static unsigned long ltq_io_region_clk_rate;
  47
  48 static unsigned long ltq_wdt_bootstatus;
  49 static unsigned long ltq_wdt_in_use;
  50 static int ltq_wdt_timeout = 30;
  51 static int ltq_wdt_ok_to_close;
  52
  53 static void
  54 ltq_wdt_enable(void)
  55 {
  56         unsigned long int timeout = ltq_wdt_timeout *
  57                         (ltq_io_region_clk_rate / LTQ_WDT_DIVIDER) + 0x1000;
  58         if (timeout > LTQ_MAX_TIMEOUT)
  59                 timeout = LTQ_MAX_TIMEOUT;
  60
  61         /* write the first password magic */
  62         ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
  63         /* write the second magic plus the configuration and new timeout */
  64         ltq_w32(LTQ_WDT_SR_EN | LTQ_WDT_SR_PWD | LTQ_WDT_SR_CLKDIV |
  65                 LTQ_WDT_PW2 | timeout, ltq_wdt_membase + LTQ_WDT_CR);
  66 }
  67
  68 static void
  69 ltq_wdt_disable(void)
  70 {
  71         /* write the first password magic */
  72         ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
  73         /* write the second password magic with no config
  74          * this turns the watchdog off
  75          */
  76         ltq_w32(LTQ_WDT_PW2, ltq_wdt_membase + LTQ_WDT_CR);
  77 }
  78
  79 static ssize_t
  80 ltq_wdt_write(struct file *file, const char __user *data,
  81                 size_t len, loff_t *ppos)
  82 {
  83         if (len) {
  84                 if (!nowayout) {
  85                         size_t i;
  86
  87                         ltq_wdt_ok_to_close = 0;
  88                         for (i = 0; i != len; i++) {
  89                                 char c;
  90
  91                                 if (get_user(c, data + i))
  92                                         return -EFAULT;
  93                                 if (c == 'V')
  94                                         ltq_wdt_ok_to_close = 1;
  95                                 else
  96                                         ltq_wdt_ok_to_close = 0;
  97                         }
  98                 }
  99                 ltq_wdt_enable();
 100         }
 101
 102         return len;
 103 }
 104
 105 static struct watchdog_info ident = {
 106         .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 107                         WDIOF_CARDRESET,
 108         .identity = "ltq_wdt",
 109 };
 110
 111 static long
 112 ltq_wdt_ioctl(struct file *file,
 113                 unsigned int cmd, unsigned long arg)
 114 {
 115         int ret = -ENOTTY;
 116
 117         switch (cmd) {
 118         case WDIOC_GETSUPPORT:
 119                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
 120                                 sizeof(ident)) ? -EFAULT : 0;
 121                 break;
 122
 123         case WDIOC_GETBOOTSTATUS:
 124                 ret = put_user(ltq_wdt_bootstatus, (int __user *)arg);
 125                 break;
 126
 127         case WDIOC_GETSTATUS:
 128                 ret = put_user(0, (int __user *)arg);
 129                 break;
 130
 131         case WDIOC_SETTIMEOUT:
 132                 ret = get_user(ltq_wdt_timeout, (int __user *)arg);
 133                 if (!ret)
 134                         ltq_wdt_enable();
 135                 /* intentional drop through */
 136         case WDIOC_GETTIMEOUT:
 137                 ret = put_user(ltq_wdt_timeout, (int __user *)arg);
 138                 break;
 139
 140         case WDIOC_KEEPALIVE:
 141                 ltq_wdt_enable();
 142                 ret = 0;
 143                 break;
 144         }
 145         return ret;
 146 }
 147
 148 static int
 149 ltq_wdt_open(struct inode *inode, struct file *file)
 150 {
 151         if (test_and_set_bit(0, &ltq_wdt_in_use))
 152                 return -EBUSY;
 153         ltq_wdt_in_use = 1;
 154         ltq_wdt_enable();
 155
 156         return nonseekable_open(inode, file);
 157 }
 158
 159 static int
 160 ltq_wdt_release(struct inode *inode, struct file *file)
 161 {
 162         if (ltq_wdt_ok_to_close)
 163                 ltq_wdt_disable();
 164         else
 165                 pr_err("watchdog closed without warning\n");
 166         ltq_wdt_ok_to_close = 0;
 167         clear_bit(0, &ltq_wdt_in_use);
 168
 169         return 0;
 170 }
 171
 172 static const struct file_operations ltq_wdt_fops = {
 173         .owner          = THIS_MODULE,
 174         .write          = ltq_wdt_write,
 175         .unlocked_ioctl = ltq_wdt_ioctl,
 176         .open           = ltq_wdt_open,
 177         .release        = ltq_wdt_release,
 178         .llseek         = no_llseek,
 179 };
 180
 181 static struct miscdevice ltq_wdt_miscdev = {
 182         .minor  = WATCHDOG_MINOR,
 183         .name   = "watchdog",
 184         .fops   = &ltq_wdt_fops,
 185 };
 186
 187 static int __init
 188 ltq_wdt_probe(struct platform_device *pdev)
 189 {
 190         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 191         struct clk *clk;
 192
 193         if (!res) {
 194                 dev_err(&pdev->dev, "cannot obtain I/O memory region");
 195                 return -ENOENT;
 196         }
 197         res = devm_request_mem_region(&pdev->dev, res->start,
 198                 resource_size(res), dev_name(&pdev->dev));
 199         if (!res) {
 200                 dev_err(&pdev->dev, "cannot request I/O memory region");
 201                 return -EBUSY;
 202         }
 203         ltq_wdt_membase = devm_ioremap_nocache(&pdev->dev, res->start,
 204                 resource_size(res));
 205         if (!ltq_wdt_membase) {
 206                 dev_err(&pdev->dev, "cannot remap I/O memory region\n");
 207                 return -ENOMEM;
 208         }
 209
 210         /* we do not need to enable the clock as it is always running */
 211         clk = clk_get(&pdev->dev, "io");
 212         WARN_ON(!clk);
 213         ltq_io_region_clk_rate = clk_get_rate(clk);
 214         clk_put(clk);
 215
 216         if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
 217                 ltq_wdt_bootstatus = WDIOF_CARDRESET;
 218
 219         return misc_register(&ltq_wdt_miscdev);
 220 }
 221
 222 static int __devexit
 223 ltq_wdt_remove(struct platform_device *pdev)
 224 {
 225         misc_deregister(&ltq_wdt_miscdev);
 226
 227         return 0;
 228 }
 229
 230
 231 static struct platform_driver ltq_wdt_driver = {
 232         .remove = __devexit_p(ltq_wdt_remove),
 233         .driver = {
 234                 .name = "ltq_wdt",
 235                 .owner = THIS_MODULE,
 236         },
 237 };
 238
 239 static int __init
 240 init_ltq_wdt(void)
 241 {
 242         return platform_driver_probe(&ltq_wdt_driver, ltq_wdt_probe);
 243 }
 244
 245 static void __exit
 246 exit_ltq_wdt(void)
 247 {
 248         return platform_driver_unregister(&ltq_wdt_driver);
 249 }
 250
 251 module_init(init_ltq_wdt);
 252 module_exit(exit_ltq_wdt);
 253
 254 module_param(nowayout, bool, 0);
 255 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 256
 257 MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
 258 MODULE_DESCRIPTION("Lantiq SoC Watchdog");
 259 MODULE_LICENSE("GPL");
 260 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);